Self-Discharge of Electrochemical Capacitors in Relation to that at Batteries

Abstract

Charged capacitors, like charged batteries, are in a state of high free energy relative to that of the discharged state, so there is a pseudo-driving force for their self-discharge. The driving force is thermodynamically the same as that which provides current and power when the capacitance is discharged through a load resistance, but then the resulting process is one of controlled discharge, which is different from that for spontaneous self-discharge on open circuit. The thermodynamic situation of instability (high free energy) of the charged state is illustrated in Fig. 18.1. The same kind of considerations apply to self-discharge of battery systems, where a similar phenomenon is well known.